Means for joining electrical conductors and the like



Dec. 13, 1949 E E, HOLKE 2,490,809

MEANS FOR JOINING ELECTRICAL CONDUCTORS AND THE LIKE Filed May 10, 1946 FIG.:L.

FIC-3.2.

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y/"i/yf/l// EUGENE IT/Lotse TTORNEY Patented Dec. 13, 1949 MEANS FOR JOINING ELECTRICAL CONDUCTORS AND THE LIKE Eugene E. Holke, St. Louis, Mo., assigner to James R. Kearney Corporation, St. Louis, Mo., a corporation of Missouri Application May 10, 1946, Serial No. 668,810

3 Claims.

This` invention relates generally to the art of joining electrical conductors, and the like, and more specifically to improved means for joining electrical conductors which involves the use of sleeve type connectors into the opposite ends of which end portions of the conductors to be joined are inserted after which the connectors are compressed, by pressure applied exteriorly thereto, onto the inserted end portions of the conductors being joined, the predominant object o the invention being to provide an improved connector of the type mentioned, which, because of its improved construction and arrangement, serves to provide a joint between electrical conductors which is of increased mechanical strength and which is of perfect electrical conductivity.

This invention is an improvement of the invention disclosed by United States Letters Patent No. 2,261,372, granted on November 4, 1941, which involves the use of a coil spring within a sleeve type connector. The sleeve of the connector of the patent mentioned above is formed of material which is malleable, while the coil spring is formed of material which is harder than the material of which the sleeve is formed and than the material of which the conductors being joined are formed, and as a result of this situation the coils of the coil spring are embedded inthe materials of the sleeve and the conductors, when the sleeve is compressed on the portions of the conductors inserted into the opposite ends oi' the sleeve, so as to securely connect the conductors together.

The y.connector of the patent referred to above has been found to perform its intended function ln a highly efficient manner, but under certain extreme conditions, which are only occasionally encountered where the connected conductors are subjected to greatly excessive strains, it has been found that slightr slippage of thev joined end portions of the conductors may develop.

The prime purpose of this invention is to provide a connector of the type disclosed by the patent mentioned above which is so constructed and arranged that the mechanical holding power of the improved connector is increased to the extent that slippage of the joined end portions of conductors is prevented even though the joined conductors are subjected to strains greatly in excess of those to which they are ordinarily `subjected in the use of connectors of the type to which the present invention relates.

Fig. 1 is a side elevation of a joint between ,a wir lof electr-ical conductors produced with the aid foi the improved connector disclosed herein.

Fig. 2 is an enlarged, fragmentary, longitudinal section taken through an uncompleted joint as it appears When the elements of the joint have been assembled, but before final completion of the joint.

Fig. 3 is a view similar to Fig. 2, but showing the joint in a completed condition.

Fig. 4 is an elevation of a coil spring which forms a part of the improved connector disclosed herein.

Fig. 5 is a cross-section, on an enlarged scale, of the coil spring shown in Fig. 4.

Fig. 6 is an enlarged, fragmentary, elevation of a portion of the coil spring shown in Figs. 4 and 5 and illustrating to better advantage cer tain knurling which forms a highly important feature of the present invention.

Fig. '7 is an enlarged, fragmentary, section illustrating a portion of a completed joint made with the aid of the improved connector disclosed herein, and showing the manner in which portions of the coils of the coil spring of the connector bite into the material of the sleeve of the connector and into the material of the joined conductors.

In the drawing, wherein is shown for the purpose of illustration, merely, one embodiment of the invention, A and B designate in Figs. l, 2, and 3, a pair of electrical conductors which in Figs. 1 and 3 are joined in accordance with the present invention, and in Fig. 2 are assembled for joining in accordance with the present invention. Associated with the conductors A and B is a connector l which includes a sleeve l that is open from end to end, said sleeve, preferably, being formed from a readily malleable material which is characterized by being a good conductor of electricity, such, for instance, as thoroughly annealed copper tubing. The sleeve l is preferably circular in cross-section, and, if desired, its opposite end portions may be slightly tapered, as illustrated. Disposed within the sleeve l' is a coil spring 2 Whose outer diameter is approximately the same as the diameter of the opening formed through said sleeve, said coil spring preferably being formed from material which is of greater hardness than the material of which the sleeve l' is formed, such, for instance, as Monel metal.

At the opposite ends of the sleeve l inwardly extended, annular anges 3 are suitably formed thereon, the opposite ends of the coil spring 2 abutting against said flanges whereby said coil spring is retained within the sleeve I when the connector l is not in use. Also, at the approximate longitudinal center of the sleeve I' a portion 4 of the wall thereof is forced inwardly by a punching operation, or otherwise, as is shown in Figs. 1, 2, and 3, the coils of the coil spring 2 immediately adjacent to said inwardly extended wall portion 4 being distorted and compressed slightly by said wall portion, as is shown to good advantage in Figs. 2 and 3.

In producing a joint between a pair of conductors, or the like, in accordance with this invention, end portions of the conductors to be joined are introduced into opposite'endsof the sleeve I of the connector I until the adjacent, inner ends of the conductorsfabut j against the coils of the coil spring 2 which are distorted by the presence of the inwardly projected wall portion 4 of said sleeve I. of the conductors have been so located within the sleeve I of the connector l the adjacent;Y inner ends of the conductors-will be located atthe approximate longitudinal 'cer'iter off 'their connector, thus insuring disposition ofthe'fp'ro'p'r length of each of the conductors within the connector to produce a secure joint. When thel endp'ortions of the conductors to be joined are disposedfwithin the connector I as described, the coils of the coil spring 2 are interposed between the' 'outer surfaces of the inserted endf portions ofthe conductors and the wall of the'openingextended through the sleeve I of the connector I, as is shownin Fig. 2. 1 f

When the connectorflv and the conductors A and B to be joined thereby are assembled as described, and as shown in Fig. 2, pressure is applied externally to the connector I by suitable means, such as forming rollers, forming dies, or otherwise, to force the wall of the sleeve I of the connector I into intimate contact with the inserted end portions of the conductors, such operation resulting in a reduction of the diameter of the sleeve of the connector. As a result of the diameter-reducing pressure to which the connector sleeve is subjected the harder coils of the coil spring 2 are embedded both in the material of the connector sleeve and in the materials of the conductors, as is shown in Figs. 3 and 7, and consequently a joint is provided between the conductors that is an interlocked mass of `materials which is of greater strength than the strength of the conductors themselves.

In order to assure a very high degree of gripping action between the coils of the coill spring 2 and the materials of nector I and the materials of the conductors A and B joined by the connector, so as to obtain the maximum mechanical holding power through the use of the improved connector disclosed herein, outer and inner surface portions of the coils of the coil spring 2 are knurled or milled, as is shown to good advantage at 5 in Figs. 5 and 6. The knurling or milling of the coils of the coil spring 2 is produced by forming short, parallel teeth, or serrations, on surface portions of the coils of the coil spring, these teeth being formed only at the outer surfaces and at the inner surfaces of the coils of the coil spring and being extended iongitudinally of the axis of the coil spring, as is shown in Fig. 6, and said teeth being extended continuously in a helical manner throughout the outer and inner surface portions of the coils of the coil spring on which they are formed.

Because of the presence of the knurling or milling 5 on inner and outer portions of the coils of the coil spring 2, the teeth provided by said- When thev end portions the sleeve I of the con-V :'sleeve l' construction where the coils of knurling or milling, bite into the material of the of the connector and into the material of the conductors joined by the connector, when the connector sleeve is compressed on the end portions of the conductors which are disposed within the connector. As a result of this situation, greatly increased gripping action is obtained in the use of the connector disclosed herein which effectively resists any tendency for the joined conductors to slip within the connector, even when said conductors are subjected to strains greatly in excess of those to which conductors joined by such connectors are ordinarily subjected.

While the foregoing description refers to a the coil spring 2 are provided with roughened, irregular, or knurled inner and outer portions, it is obvious that if desiredroughened, irregular, or knurled surface portions may be provided only at inner portions of the coils of the Vcoil spring, or only at outer portions of said coils of said coil spring. "1^

I claim: f j

1. A connector for producing joints between electrical conductors comprising a hollow elonf gated element into the opposite endsof which end portions of a pair of conductors to be joined are inserted, a coil spring disposed within said hollow elongated element in such mannery that the coils of said coil spring are interposed between the inner face of said hollowelongated element and the outer surfaces of the inserted portions of conductors to be joined by the con-'- nector, said coil spring being formed ofl m a' terial which is harder than the materials from which the hollow elongated element and the conductors are formed, said hollow elongated element being formed of readily malleable ma# terial and being adapted to be compressed onto the inserted portions of the conductors to be joined so as to cause the coils of the coil spring to be embedded in the material of both the hollow elongated element and the inserted portions of the conductors, means for retaining the coil spring in its proper position within said hollow elongated element when the connector-is not in use, and knurled portions formed on th lcoils of said coil spring which serve to increasethe gripping action of said coils of said coil spring with respect to said hollow elongated element and with respect to the inserted portions ofthe conductors joined by the connector.

2. A connector for producing joints between electrical conductors comprising a hollow elonf gated element into the opposite ends of which end portions of a pair of conductors to be joined are inserted, a coil spring disposed within' said: hollow elongated element in such manner-thatl the coils of said coil spring are interposed between the inner face of said hollow elongated element and the outer surfaces of the inserted portions of conductors to be joined by the connector, said coil spring being formed ofma-f terial which is harder than the materials from which the hollow elongated element and the con-f ductors are formed, said hollow elongated ele` ment being formed of readily malleable material* and being adapted to be compressed onto the so as to cause the coils of elongated element and the inserted portions off the conductors, means for retaining the coil spring in its proper position within said hollowl elongated element when the connector is not use, and knurling formed on opposed surface portions only of the coils of said coil spring which serve to increase the gripping action of said coils of said coil spring with respect to said hollow elongated element and with respect to the inserted portions of the conductors joined by the connector.

3. A connector for producing joints between electrical conductors comprising a hollow elongated element into the opposite ends of which end portions of a pair o conductors to be joined are inserted, a coil spring disposed within said hollow elongated element in such manner that the coils of said coil spring are interposed between the inner face of said hollow elongated element and the outer surfaces of the inserted portions of conductors to be joined by the connector, said coil spring being formed of material which is harder than the materials from which the hollow elongated element and the conductors are formeel, said hollow elongated element being formed ci readily malleable material and being adapted to be compressed onto the inserted portions of the conductors to be joined so as to cause the coils of the coil spring to be embedded in the material of both the hollow elongated element and the inserted portions of the conductors, means for retaining the coil spring in its proper position within said hollow elongated element when the connector is not in use, and knurling ormed on opposed surface portions only of the coils of said coil spring which serve to increase the gripping action of said coils of said coil spring with respect to said hollow elongated element and with respect to the inserted portions of the conductors joined by the connector, the surface portions of said coils of said coil spring which are located between said opposed knurled surface portions being substantially smooth.

EUGENE E. HOLKE.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,727,108 Julius Sept. 3, 1929 2,261,372 Holke Nov. 4, 1941 

